Show a different banner in chrome://settings for extension-controlled settings.

chrome/browser/resources/options/font_settings.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('options', function() {
 
   var OptionsPage = options.OptionsPage;
 
   /**
    * FontSettings class
@@ skipping 135 matching lines @@
         text = items[i][1];
         if (text) {
           selected = value == selectedValue;
           element.appendChild(new Option(text, value, false, selected));
         } else {
           element.appendChild(document.createElement('hr'));
         }
       }
 
       // Enable if not a managed pref.
-      if (!element.managed)
+      if (!element.controlledBy)
         element.disabled = false;
     }
   };
 
   // Chrome callbacks
   FontSettings.setFontsData = function(fonts, encodings, selectedValues) {
     FontSettings.getInstance().populateSelect_($('standard-font-family'), fonts,
                                                selectedValues[0]);
     FontSettings.getInstance().populateSelect_($('serif-font-family'), fonts,
                                                selectedValues[1]);
@@ skipping 33 matching lines @@
     FontSettings.getInstance().setUpFontSample_($('minimum-font-sample'), size,
                                                 null, true);
   };
 
   // Export
   return {
     FontSettings: FontSettings
   };
 });